In semiconductor devices, recombination is a process in which an electron and a hole annihilate each other. Recombination may be radiative, wherein the energy is converted to electromagnetic radiation, or non-radiative, where the energy is ultimately transferred to the semiconductor as heat.
Semiconductor bipolar devices can in particular suffer from non-radiative surface recombination at exposed surfaces, such as surfaces exposed during device fabrication through etch methods, and such non-radiative surface recombination can lead to poor performance, particularly in, for example, optoelectronic applications such as LED (light emitting diode) devices.
Small device geometries can further exacerbate this problem, as a higher volume fraction of the device's active region is close to the surface of the device, and thus increasing the probability of surface recombination.